This paper presents, for a system consisting of a gantry crane, the sizing of an Ultracapacitor (UC) based storage sytem, and its performance test using a simulated model of the system considered as a multi-axis drive. Preliminary examination of different operating processes has been done. For each proccess were considered the different drives refered to the toughest conditions, and the diagrams of torque, power and energy were built for each of them. Two different approches were used for the UCs sizing. The first approach consists on considering the peak power during each operating proccess and consequently the energy furnished by the system during these power peaks. The second approach consists on considering the energy of the lifting process (UCs recharge).